It's a scientific test and as such, does have to be on alike for like basis. You would also be testing bullets made over 30 years later and without knowing the conditions used in the first tests; for instance, did the testees wash their hands? If so, what with? All you can say with any new test is that you either got similar or completely different results, not that it makes the Elliot test redundant.
Sheila had reduced levels of lead in comparison, which could have come from other sources, she had a higher level on her right hand which was the hand on the rifle.
I don't think there was anything remotely scientific about it hence such tests aren't offered by FSP's and don't feature in forensic text books. It's impossible to say he/she did/didn't handle X when he/she may well have handled Y made of the same material.
The cartridges today are manufactured to the same spec as they were 30 plus years ago.
Yes the testees did wash their hands but washing alone doesn't remove lead from hands. The important thing is that control swabs were not taken from testees hands to determine the levels of lead already on hands prior to the handling and loading test.
The testees and SC's right hand showed higher levels of lead presumably because they were all right handed but there's no evidence the lead came from handling/loading the bullets or SC's right hand in contact with rifle. It could just as easily have come from handling everyday items many of which contained lead in the mid-80's.
The swabbing kit used on SC was for GSR not lead from handling/loading cartridges. Where did DC Hammersley swab SC's hand? GSR distributes widely like a dust cloud so there would be no need to be specific. Elliot may well have swabbed across testees fingertips which would be an area specific to handling and loading cartridges.
Whichever way you look at it Elliot's test/results will not stand up to scutiny at the next appeal.
I wouldn't mind betting its this sort of thing parliament was referring to when it identified high profile quality failures at FSS in the 1980's.